Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1325 
GIC
uncertain (ending with a star?)
rectangular 
5–5.5 x 3–3.5 mm 
on a coin of Hadrian from Ilium 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC III, 1573 Show 1573 6 3
RPC I, 4943 Show 4943 14 1